The present invention relates generally to methods for fabrication of compressor cases for gas turbine engines, and more particularly to a method for fabricating a split compressor case to avoid ovalization during hot operation of the engine.
A common configuration for a compressor case of a gas turbine engine includes a split case structure including two case halves assembled along a common axial plane at a pair of flanges. Operating tests on certain engines incorporating this structure indicate a potential problem with ovalization of the compressor case during hot operation. Simulations of the compressor split case indicate that non-uniform deflections may be related to flanges which join the case. One solution is to machine the split case with an oval internal shape which would theoretically compensate for case ovalization at hot operating temperatures, but would require multiple machining passes on the compressor case.
The invention solves or substantially reduces in critical importance problems with existing fabrication methods for split compressor cases by providing methods for machining and assembling an engine case in an out-of-round condition utilizing suitably shaped shims at the flanges to produce a case that will distort to the correct contours at engine operating temperatures.
It is therefore a principal object of the invention to provide a method for fabrication of a split compressor case for a gas turbine engine.
It is a further object of the invention to provide a method for fabrication of a split compressor case to avoid ovalization during hot operation of the engine.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.